\documentclass{article}
\usepackage[T2A]{fontenc}
\usepackage[cp1251]{inputenc}
\usepackage[english,bulgarian]{babel}
\usepackage{pifont}
\usepackage{pstricks}
\newpsstyle{gridstyle}{subgriddiv=0,gridcolor=lightgray,griddots=10,gridlabels=0pt}
\usepackage{pst-pdf}
\usepackage{tikz}
\usetikzlibrary{shapes,arrows,calc}

\begin{document}
\begin{pspicture}[showgrid=false](0,0)(1,13.2)
% Define block styles
\tikzstyle{dia} = [diamond,shape aspect=2, draw,thick, fill=blue!20,text width=5em, text badly centered, node distance=2.5cm, inner sep=0pt,]
\tikzstyle{rec} = [rectangle, draw,thick, fill=blue!20,text width=14em, text centered, rounded corners, minimum height=2.5em]
\tikzstyle{line} = [draw, -latex']
\tikzstyle{round rec} = [draw, rounded rectangle,fill=orange!20,draw=orange, thick, node distance=3cm,minimum height=2em, text width=5em, text centered]
\tikzstyle{del} = [draw=none,fill=none, inner sep=-8pt,outer sep=0pt, minimum size=2pt, node distance=6.3em,minimum height=0.1mm]

\pgfsetendarrow{\pgfarrowlargepointed{2.5pt}}


\begin{tikzpicture}[node distance = 1.5cm, auto]

    % Place nodes
    \node [round rec] (A) {Начало};
    \node [rec, below of=A] (B) {PC \ding{213} адресна магистрала};
    \node [rec, below of=B] (C) {Инструкция \ding{213} IR};
    \node [dia, below of=C, node distance=6em] (D) {Инстр. за преход?};
    \node [dia, below left of=D, node distance=8em] (E) {Условен преход?};
    \node [rec, below right of=D, node distance=8em, text width=6em] (F) {Изпълнение на операцията};
    \node [dia, below of=D, node distance=12em] (G) {У-то изпълнено?};
    \node [rec, below left of=G, text width=8em, node distance=8em] (H) {PC = адреса на прехода};
    \node [rec, below right of=G, text width=8em, node distance=8em] (I) {PC = адреса на следващата инструкция};
    \node [del, below of=E] (zero_1) {};
    \node [del, below of=F] (zero_2) {};
    \node [del, below of=H, node distance=4em] (zero_3) {};
    \node [del, below of=I, node distance=4em] (zero_4) {};
    \node [del, below of=A, node distance=2em] (zero_6) {};



    % Draw edges
    \path [line,thick] (A) -- (B);
    \path [line,thick] (B) -- (C);
    \path [line,thick] (C) -- (D);
    \path [line,thick] (D) -| node [near start,above] {да} (E);
    \path [line,thick] (D) -| node [near start,above] {не} (F);
    \path [line,thick] (E) -| node [near start] {да} (G);
    \path [line,thick] (E) -- node [near start, left] {не} (H);
    \path [line,thick] (G) -- node [near start, above] {да}(zero_1);
    \path [line,thick] (F) -- (I);
    \path [line,thick] (G) -- node [near start] {не}(zero_2);
    \path [line,thick] (H) -- (zero_3);
    \path [line,thick] (I) -- (zero_4);
    \draw [line,thick] ($ (zero_3.south) + (0mm,0pt) $)-- ++(6.2,0) -- ++(0,12)  |- ($ (zero_6.east) + (0mm,0pt) $);

\end{tikzpicture}
\end{pspicture}

\end{document} 